Varus and valgus deformities of the foot in cerebral palsy (1982).

Varus and valgus deformities of the foot in cerebral palsy (1982) Another in our series of commentaries on notable papers from the DMCN archives. Deformities of the foot and ankle are common among patients with cerebral palsy. Equinus due to contracture of the gastrocne-mius-soleus muscle is the most common: it has been estimated that some 20 to 25 per cent of all children with cerebral palsy will require surgery for this deformity and the results are predictably good. Varus and valgus deformities are less easily corrected surgically , and it is also less easy to explain their development. An equinovarus deformity usually is attributed to overactivi-ty of tibialis anterior or tibialis posterior in the presence of equi-nus. Equinovalgus is explained by the 'bowstring' theory, which states that: 'in the presence of an equinus contracture the hind-foot is forced into the valgus position when the forefoot touches the ground. This occurs because of the bowstring effect of the triceps surae on the ankle and subtalar joints. The calcaneum then rotates under the talus, which then drops into a more vertical position on losing the support of the sustentaculum tali.' Two objections can be raised against this theory. (1) equinovalgus deformities are seen in children who have never walked; and (2) hemiplegic children who are fully mobile seldom develop a val-gus deformity, in spite of equinus commonly being present. From clinical observations we have noted that whereas hemiplegia typically produces an equinovarus deformity, dip-legia and quadriplegia are characterised by an equinovarus foot. This was confirmed in a retrospective study of 230 children who had had foot surgery at the Hospital for Sick Children, Toronto. If either varus or valgus deformity was present, 94 per cent of affected hemiplegic patients were in varus, whereas for those with diplegia and quadriplegia, 64 per cent were in valgus. We also noted that hemiplegic children often show signs of tibialis overpull, whereas those with diplegia or quadriplegia seldom do. This suggests a possible reason for the different pattern of deformity in the two groups; it seemed to us that the fundamental difference lay not in muscle contractures or mobility, but in the function of tibialis posterior. Commentary To understand the significance of this paper it is important to put it in its historical context. In the early 1980s, orthopaedic surgeons were only just starting to come to grips with the concept of dynamic assessment of cerebral …